1. Field of the Invention
Generally, the invention relates to light sources for collimating reflector type flashlights. More specifically, the invention relates to such light sources wherein at least one light emitting diode produces the light and means are provided for diffusion of the produced light to a collimating reflector for collimation of the produced light into a beam of light.
2. Description of the Prior Art
It is estimated that in 1998 over two hundred (200) million collimating reflector type flashlights were produced. Conventionally known flashlights which utilize a collimating reflector operate with incandescent lamps, (bulbs), which have a coiled filament placed in a geometric position compatible with the focal point of the collimating reflector.
Incandescent lamps, (bulbs), are constructed with a `light center length` or LCL which is defined as the best strait line that can be passed through the majority of the lighted coil. A collimated beam of light, defined by `beam candle power`, is created when the coil is properly positioned to a focal point of the collimating reflector.
Collimating reflector flashlights utilizing light emitting diodes and the principles of the present invention will create a vast new market for light emitting diodes.
Conventional light emitting diodes generally are currently limited to small flashlights such as key chain type lights, small pen lights and small flashlights which do not utilized collimating reflectors to enhance the collimazation of the produced light. This is due primarily to the narrow view angle of the produced light and the lack of utilization of light bending surfaces or other diffusion methods. Attempts have been made to use light emitting diodes in incandescent lamp (bulb) bases. These attempts have been limited to providing a convenient light source for use in existing flashlights where the produced light does not interact with the collimating reflector of those flashlights. It is important to note that these replacement incandescent lamps using light emitting diodes heretobefore have not been designed to operate with the collimating reflector to produce a beam of light.
Conventional light emitting diode light sources lack light bending surfaces to broaden the narrow view angle of the produced light. The light emitting diode, in conventional form, does not make a satisfactory source of light for conventional flashlights because the point source of light is on a plane. The conventional light emitting diode is formed by the deposition of semiconductor materials and phosphors to a substrate in a planar configuration which inhibits use as a broad spectrum light source. Conventional collimating reflector flashlight require the broad spectrum light source.
The Polar light distribution of light emitting diodes is at best one hundred and twenty-five (125) degrees and most commonly fifteen (15) degrees. Convention collimating reflector flashlight require a polar distribution of three hundred and sixty (360) degrees, (radially), for maximum efficiency.
Conventional light emitting diodes use an acrylic or plastic molded lens package without an indices of refraction to broaden the angle of light transmission. Diffusion utilizing translucent coatings or finishes have been used to a minor degree with limited success.
Various methods exist in the art to alter the angle of projection of light. Such conventional methods to alter the angle of projection of light include lighted panels and annunciators, amongst others. Your applicant is unaware of utilization of such methods with light emitting diode light sources wherein the produced light may be efficiently used with flashlights having a conventional collimating reflector.
Light emitting diodes which produce white light, offer a new and superior light source in that they provide superior lamp life and battery run time. Conventional light emitting diode light sources are unsatisfactory for direct use in flashlights with collimating reflectors due to a narrow viewing angle of the light emitting diode, generally between fifteen (15) degrees and thirty (30) degrees. When the conventional light emitting diode is positioned facing away from the collimating reflector, this narrow viewing angle projects the available light beyond the walls of the collimating reflector. When the conventional light emitting diode is positioned facing toward the collimating reflector, this narrow viewing angle projects the available light to only a portion of the wall of the collimating reflector. The curved collimating reflector wall therefore cannot properly act upon the produced light of conventional light emitting diode light sources to collimated the light beam.
For the above mentioned reasons, substitution of a conventional light emitting diode light source for the conventional incandescent lamp in flashlights, where the flashlight has a curved collimating reflector, will fail because the substitute conventional light emitting diode light source and the existing curved collimating reflector will fail to cooperate to produce an acceptable collimated light beam.
Light emitting diodes are superior to conventional incandescent lamps, (bulbs), because they: 1) require less power, 2) have a longer life, 3) have a greater resistance to both shock and vibration, 4) provide generally higher color temperature and 5) provide higher lumens per watt.
Due to the long life of the light emitting diode light source it is conceivable that a flashlight having a light emitting diode as the light source would never need replacement. Due to the lower power requirement of the light emitting diode light source, batteries of such flashlights would last up to 10 times as long as batteries of conventional flashlights. This combination provides for considerable cost and environmental savings.
A great need exists for collimating reflector type flashlights which have low current draw and long life. Numerous attempts have been made to produce collimating reflector type flashlights which have the desired low current draw and long life. Utilization of the designs of the present invention will fill a long felt need and create a new market niche. The present invention substantially fulfills these needs.